Throws a Parse Error under PhantomJS

Loading CSSOM under PhantomJS 1.8.1 either via

```
$ phantomjs cssom.js
```

or

```
$ phantomjs
> phantom.injectJs("CSSOM.js");
```

returns a `SyntaxError: Parse error`

Removing the initial `'use strict';` solves that problem.

I tried going through jshint to find a possibly offending issue, but it shows me too many warnings and stops before completing.
